Immediately after the rock is released, is the magnitude of its acceleration greater than, less than, or equal to?

equal to gg less than gg greater than gg

Equal to g.

Explanation:

As the rock is thrown, the only force acting is gravity hence the rock accelerates at the rate of g. No external forces act on the rock since its motion is in line with gravity.

The initial velocity of the rock however would be greater than had it just been released so it would strike the bottom before a rock that was simultaneously dropped. The acceleration does not change once thrown.